Modern electronic systems frequently use battery backup systems as a safety feature to prevent loss of service due to a failure of a primary power source. To provide effective protection requires the use of fully charged batteries capable of supplying the needed backup power for some acceptable time interval. In some instances, however, the power loss duration may exceed the time limit capability of the reserve battery power and it may be desirable to replace the discharged battery to provide further service or test system operability. This additional requirement requires that the battery backup system have the capability of charging batteries and the ability to activate the system at least momentarily for test purposes with a replacement battery even in the continued absence of primary power. Such testing requirements may occur in communication systems where it is necessary to determine the operativeness of the communication system during the loss of primary power for extended intervals exceeding battery reserve power capabilities.
Most systems having battery reserve power include circuitry to disconnect the battery at some point during an extended loss of primary power to protect the battery from permanent damage, such as cell reversal, after it has discharged to some threshold voltage level. Replacing a discharged battery with a fresh battery in such a system arrangement, and testing the operativeness of the system before restoration of primary power normally requires the switching of the battery terminals into the active circuitry for a short interval of time. This testing is often performed before the restoration of primary power to the system. Frequently this is performed with a manual switching arrangement. Such an arrangement not only requires an operator's understanding of circuit processes, but it also requires readily accessible manual switches and associated circuitry. If properly ergonomically designed, such manual switch arrangements may be spatially inefficient with respect to the spatial requirements of the circuit itself. Provision of the needed manual switching capability may indeed seriously compromise spatially efficient packaging of the circuitry itself.